1. Field of the Invention
The invention relates to an adjustable-length column for chairs, tables or the like, having an upright tube and a pneumatic or hydropneumatic length-adjusting element disposed in it concentrically with a common central longitudinal axis, the housing of the length-adjusting element being radially supported in the upright tube and guided displaceably in the direction of the axis, and the piston rod of the element being secured in the vicinity of its free end to a bottom plate of the upright tube in the direction of the axis, wherein in the vicinity of the end of the upright tube remote from where the housing leaves the upright tube, the bottom plate is supported on a rim of the upright tube protruding radially inward into the upright tube and defined by an end face.
2. The Prior Art
Adjustable-length columns of this kind are known from German Patent No. 19 31 012 (corresponding to U.S. Pat. No. 3,711,054) and European Patent No. 0 133 524 and are widely used. In these known columns, the bottom plate is welded into the upright tube. This kind of manufacturing method is extremely complicated. Attempts have therefore already been made to provide a bead on the lower end of the upright tube, with the bottom plate set onto the bead. At the top, the columns are fastened by means of protrusions that are made by indenting the upright tube. Another previous attempt to avoid time-consuming welding comprised crimping the lower rim of the upright tube inward at approximately a right angle, and placing the bottom plate on that rim (German Utility Model 76 23 283).